Chemical apparatus



Feb. 21, 1950 w. o. LUERTZING CHEMICAL APPARATUS Filed March 24, 1948 m mos ATTORNEYS Patented Feb. 21, 1950 CHEMICAL APPARATUS Walter, Luertzing; Vineland; Ni .L, assig-noltr to; LurexManufa-ctur n o nanyi V ne an la. a corporatiqnoiNew. Jersey ApplicationM'arch 24, 1948; SerialNo. 16,l1l

This invention relates to glass articles adapted to be assembled withothers with air-tight connections of the ground tapered plug and socket type, examples of such articles being lengths of tubing employed in chemical apparatus, adapters, stoppers, and the like. More particularly, the invention is concerned with a novel glass article having afrusto-conical groundsurface, the article being so formed that it isnot. liable to, be damaged by chipping atv the small end. of: the ground surface durin handling and use; The invention. also includes a method, by which such articles may be made easily and at no more cost than prior similar articles. The new articles may be of various kinds, depending upon the use to which they are to be put, and, since a length of tubing with a ground tapered portion of plug shape is typical, that form of the article of the invention will be illustrated and described in detail.

At the present time, it is the practice, in making lengths of glass tubing to be used in chemical apparatus and provided with ground frusto-conical surfaces, to heat the end portion of a straight length of tubing and work the softened glass by a suitable tool to form a blank having a portion of increased wall thickness, which terminates at the end of the blank and has an outer diameter tapering toward that end. The end surface of the blank is smooth and, in finishing the article, the outer surface of the thickened portion is ground to frusto-conical form with the ground surface meeting the end surface. The end of the blank is so formed that the angle between the ground and smooth end surfaces on the article is ordinarily a right angle or less and this makes the outer end edge of the article so sharp that it is delicate and easily damaged by chipping.

The present invention is directed to th provision of a glass article with a ground surface of frusto-conical form, which is not liable to be damaged along the edge of the surface at the small end of the ground surface. The desired result is achieved by giving the blank, of which the article is to be made, a novel shape at the end of the portion to be ground and then grinding the blank in such a manner that the surface of the article beyond the end of the ground surface is smooth, extends outwardly beyond the ground surface, and, with the latter, defines an angle greater than a right angle.

For a better understanding of the invention, reference may be made to the accompanying drawing, in which Fig. 1 is a view in longitudinal section through so Fig; 2 i's aalongitudinal. sectional View. through.

the finished article made from the blank of. P523111 and Fig; 3 is a side elevation, on a. reduced scala.

of the end portion of; thefinishedarticleshown.

ill-Fig; 2;

The articleshown in the: drawingis: a

with a" portion of plug form havinga. frusto.-coni.-:

cal ground surface, so thatt the end of the tubingmay be inserted inaground v tapered socket; forv example, in the neck of a vessel, to make an airtight connection. In the production of such an article, a length of straight tubing I0 is used and the end portion of the tubing is heated and worked with a tool to form an enlargement I I of increased wall thickness and having an outer circumferential surface I2 of frusto-iconical form. At its end, the surface of the blank is formed with a circumferential zon [3, which extends backwardly from the end and outwardly at an acute angle to the axis of the tubing. From the inner edge of the zone extends a curved surface I4 which connects the surface of the zone with the inner surface 15 through the blank.

To convert the blank to the finished article, the outer surface of the portion of increased thickness is ground to frusto-conical form, the taper of the ground surface corresponding to that of the socket in which the article is to be mounted. In the grinding operation, a quantity of glass is removed circumferentially from the blank and the operation is restricted, so that the extension of the ground surface will intersect the zone [3. As a result, the article has a smooth end surface I5, which projects outwardly beyond the small end of the ground surface and inhibits chipping of the adjacent end of the article The taper of the ground surface is such that a generatrix of the surface makes a small angle with the longitudinal axis of the article, and the angle a between the ground surface and the surface of the zone I3 at the end of the article or a plane tangent to the smooth end surface of the blank at its intersection with the ground surface, is greater than a right angle. As a result, the outer end edge I! of the article is comparatively blunt and not liable to be damaged durin shipment or use of the article.

It will be apparent that the zone l3 need not be of frusto-conical form and ordinarily it is not precisely so but of somewhat spherical curvature on a large radius. The shape of the article belength;-v of glass tubing, which is providedaatmnexend;

acute the circumferential zone, which, with the frustoconical ground surface, defines an obtuse angle.

I claim:

1. A glass article which comprises a tubular body having a smooth unground circumferential surface at one end, said surface including a zone having an outer surface portion extending back- 4 circumferential surface of appreciable extent extending from the small end of the frusto-conical ground surface to the adjacent end of the article, the included angle between the ground and smooth unground surfaces being greater than a right angle.

3. In a glass article including a tubular portion having an extended ground circumferential surface of frusto-conical form tapering in diameter toward one end of said tubular portion and terminating close to but short of said end, means for inhibiting chipping of said end of the tubular portion which comprises a smooth unground circumferential surface of appreciable extent extending from the small end of the frustoconical ground surface to and around said end wardly from said end and outwardly at an acute angle to the axis of the blank and an inner SLl1- face portion extending backwardly from said end and inwardly at an obtuse angle to the inner periphery of the end portion of the article, the body also having a ground circumferential surface of frusto-conical form, the small end of the ground surface meeting said zone with the angle between the ground surface and the surface of the zone greater than a right angle.

2. In a glass article having an extended ground.

circumferential surface of frusto-conical form tapering in diameter toward one end of the article and terminating close to but short of said end, means for inhibiting chipping of said end of the article which comprises a smooth unground of the tubular portion to the bore thereof, the included angle between the ground and smooth unground surfaces being greater than a right angle.

WALTER 0. LUERTZING.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 914,244 Conradson Mar. 2, 1909 2,180,640 Mikalson Nov. 21, 1939 2,154,574 Martin Apr. 18, 1939 2,427,849 Garwood Sept. 23, 1947 

